Improving the power density of a Geobacter consortium‐based microbial fuel cell by incorporating a highly dispersed birnessite/C cathode

BACKGROUND Microbial fuel cell (MFC) power production is limited by the cathodic oxygen reduction reaction (ORR). The quest for platinum‐free materials for improving the cathodic ORR in MFCs is a challenging task. Birnessite‐type MnO2/carbon cathodes in MFCs have been rarely reported so far. In this work, a birnessite/C cathode was tested in a MFC. RESULTS A birnessite/C cathode was synthesized (using a rapid, facile and low‐cost method) and its structural and morphological characteristics were assessed. The ORR on such a cathode was investigated using linear sweep voltammetry in a catholyte of 0.8 mol L–1 Na2SO4, pH 2 (same conditions as those of experimental MFCs). The current density values were higher than those for a plain C cathode. The volumetric power density improved from 224 to 6201 mW m−3 on replacing the plain C cathode with the birnessite/C cathode in a MFC. Deltaproteobacteria were found at the C anode and they were associated with the high power densities obtained. CONCLUSIONS Birnessite/C is a promising cathodic electrode because its synthesis is straightforward, it is not expensive and it could promote the ORR and improve the power density in MFCs. © 2020 Society of Chemical Industry